This application claims the priority benefit of Taiwan application serial no. 90105378, filed on Mar. 8, 2001.
1 Field of the Invention
The invention relates to a print head used in a printer. More particularly, the present invention relates to an inkjet print head for a printer.
2 Description of the Related Art
With reference to U.S. Pat. Nos. 4,490,728, 4,809,428, 4,596,994, 4,723,129, 4,774,530, and 4,863,560, a conventional inkjet print head principally comprises: a capillary tube, an orifice plate, and a resistor. The resistor rapidly heats under a voltage pulse, which has a pulse width of a number of micro-seconds. The heating of the resistor is properly controlled such that the temperature of the ink is taken to a vapor nucleation point. The vapor bubble generated, under proper control, then causes ejection of a droplet of ink. With the conventional thermal inkjet technology as described above, a frequency of several kHz can be attained. Traditionally, conventional inkjet print heads typically comprise two types as described hereafter.
Referring to FIG. 1, a construction diagram schematically shows a conventional side-shooting inkjet print head. The conventional side-shooting inkjet print head comprises a thermal barrier layer 22, a thermal resistor layer 24, a conductive layer 26, and an insulating layer 28, sequentially formed on a substrate 10. Through an adequate patterning processes, a plurality of resistors 20 are formed on the substrate 10. A plurality of ink channels 32, respectively comprising the resistors 20 therein, are formed in an isolation layer arranged above the insulating layer 28, the ink channels being covered by a nozzle plate 40. When a resistor 24 rapidly heats, a vapor bubble 50 is generated. The rapid expansion of the vapor bubble 50 causes ejection of a droplet of ink 52. As shown in FIG. 1, the droplet of ink is ejected from the side of the inkjet print head, along the ink channel.
Referring to FIG. 2, a construction diagram schematically shows an up-shooting inkjet print head. The up-shooting inkjet print head of FIG. 2 differs from that described above in FIG. 1 in that the up-shooting inkjet print head has a plurality of orifices 42 in the nozzle plate 40 that respectively face the resistors 20. When a resistor 20 heats the ink in the ink channel 32, the vapor bubble 50 that is generated causes the ejection of the droplet of ink 52 from the orifice 42 facing the resistor 20.
Both foregoing conventional inkjet print head structures are fabricated according to conventional methods as follows. The thermal barrier layer 22 is usually a silicon dioxide (SiO2) layer formed on the substrate 10, which is usually a silicon (Si) substrate, through various method known in the art. Then, the thermal resistor layer 24 and the conductive layer 26 are deposited by typical sputtering. The resistors 20 are formed by photolithography and etching processes applied to the thermal resistor layer 24 and conductive layer 26. The insulating layer 28 is then formed on the resistors 20 to prevent any electrochemical reaction between the resistors and the ink. The ink channels 32 are conventionally formed by specific laser drilling, sand blasting, or ultrasonic milling of a dry film arranged on substrate 10. Finally, the inkjet print head structure is completed by aligning and bonding the nozzle plate 40 over the substrate 10, covering the ink channels 32.
The conventional inkjet print head, such as the above-described, has at least the following drawbacks. Specific machining processes and aligning-bonding are necessary to fabricate the nozzle plate, which substantially increases the fabrication cost, and does not allow for an all-batch process. Besides, the ink channel is formed through using machining processes that can generate residual material and deteriorates the efficiency of the inkjet print head.
An inkjet print head structure that, at least, can overcome the above drawbacks is thus needed.
A major aspect of the present invention is to provide a back-shooting inkjet print head that can allow for an all-batch process and a low cost of materials.
To attain the foregoing and other objects, the back-shooting inkjet print head, according to an embodiment of the present invention, comprises: a first substrate having a plurality of thermal resistors formed on a back surface thereof, and a plurality of orifices formed through the first substrate and respectively located proximate to the resistors; an isolation layer having a plurality of ink channels formed therein, wherein the isolation layer is arranged onto the back surface of the first substrate such that the region of each ink channel covers the region of one of the resistors and one of the orifices therein; and a second substrate having an ink supply window formed therethrough, wherein the second substrate is arranged on the isolation layer covering the ink channels, such that the ink supply window, connected to the ink channels, is located at one side of the resistors while the orifices of the first substrate are located at the other side of the resistors facing the second substrate.
To attain the foregoing and other objects, the back-shooting inkjet print head, according to another embodiment of the present invention, comprises: a first substrate having a plurality of thermal resistors formed on a back surface thereof, and a plurality of orifices formed through the first substrate and respectively located proximate to the resistors; and a second substrate having a plurality of ink channels formed on a front surface thereof and an ink supply window, connected to the ink channels, formed on a back surface thereof, wherein the second substrate, by its front surface, is arranged on the back surface of the first substrate, thereby covering the ink channels, such that the ink supply window is located at one side of the resistors while the orifices of the first substrate are located at the other side of the resistors facing the ink channels of the second substrate.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.